FI67633B - FOERFARANDE OCH ANORDNING FOER IDENTIFIERING AV FOEREMAOL - Google Patents

Abstract

1. Method of identifying articles, which appear in any position and orientation and at any time at an image aperture and each have a designating area or panel on a surface which is facing the image aperture, which panel comprises symbols (52) in at least one datum track (51) and at least one contrasting line pattern (54), which characterizes the positon and the orientation of the datum track and has a plurality of parallel lines of different spacing and/or line width, in connection with which the image aperture is scanned line by line (60) and a binary video signal corresponding to the scanned contrast line pattern and the following symbols is produced, the image aperture in the first step of the method being scanned at different angles until a prescribed contrasting line pattern is detected, in the second step of the method, the position alignment of the data track relatively to the image aperture is established, and in the third of the method, a grid scanning is effected in the direction of the data track and the symbols are read off and decoded, characterized in that, - for the detection of the constrast line pattern (PIC), the interval lengths of overlapping intervals (Figs. 11 to 14) of the video signal and in each case comprising at least one light-dark region are measured and portrayed in the form of binary counter readings (TC1 to TC4), - that the counter readings (TC1 to TC4, Fig. 6) address a two-dimensional table (Fig. 10) which is stored in a store (28 in Fig. 7) and in which is contained an expectation zone with criteria for a prescribed ratio between two successive interval lengths of the intervals (11 to 14), - that the counter reading (TCN) corresponding to an interval length (IN) addresses one line of the table and the reading corresponding to the following interval length (IN+1) addresses one column of the table, - that a coincidence signal (LPIC1, LPIC2, LPIC3) is produced when the relation of the two respectively following interval lengths lies in a prescribed value range, and - that a recognition signal (PIC OUT Fig. 9) is delivered when a coincidence signal (LPIC1, LPIC2, LPIC3) is produced with a number of successive addressing steps which is prescribed by the contrast line pattern (PIC).

Description

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Patent and Registration Office ........ . __. .....

_ · (44) Date of issue and date of publication. -.

Patent- och registerstyreleen 'An »Okan utlagd och utl.skrlften pubticerad 31 .12.84 (32) (33) (31) Requested privilege — Begird prlorltet 19-04.79

Federal Republic of Germany-FörbundsrepubIiken Tyskland (DE) P 2915732.2 Proven-Styrkt (71) Scantron GmbH 6 Co. Elektronische Lesegeräte KG, Legienstrasse 14, 6230 Frankfurt-Hoechst, Federal Republic of Germany Förbundsrepubliken Tyskland (DE) (72) Klaus Wevelsiep ·, Kriftel, Germany L ii tt ttavo ta-Förbundsrepubl iken Tyskland (DE) (7 * 0 Ruska & Co Oy ( 5 * 0 Method and apparatus for identifying objects -Förfarande och anordning för identifiering av föremäl

The invention comprises a method and apparatus for identifying objects which appear on the screen in any position and direction and at any time and in each case indicate on the screen surface an identification field (50) comprising characters in at least one data line (51) and at least one contrast line pattern (5 * 1) , which is an indication of the position and direction of the data line and in which the contrast line pattern has a plurality of parallel lines at different distances and / or line widths, sweeping the screen line by line and generating a binary video signal corresponding to identifying a predetermined contrast line pattern, the second method step determining the position and orientation of the data line relative to the screen, and the third method step performing a raster scan in the direction of the data line and reading and decoding the characters.

Such methods and equipment are already known. Identifiable objects are, for example, merchandise, department store articles or the like which are identifiable in a machine-readable form 2 67633. For this purpose, tags are affixed or placed on the objects, which are printed with characters of a machine-readable code, e.g. an OCR code. Such an identifier may consist of quality, dimension, price information, article number, etc. This identification information is somehow placed on the surfaces of the objects.

Such tags are only difficult to read by machine, because the objects are different in size and because these tags are placed, for example, on adhesive labels at different places in the object. Thus, when reading a tag, it cannot be assumed that the tag is available in a certain position at a certain time and in a fixed direction. Reading these tags is thus not comparable to reading punch cards or the like, where the card is available in a well-defined reading position for well-defined times. In the above case, the opposite happens. The data field in the object now appears more or less at a roughly specified location, and the direction of the data field is also relatively arbitrary.

Such methods and equipment for identifying objects are installed, for example, at the checkout points of supermarkets, etc. to enable the price and / or article number of the objects which the customer wants to buy and has brought to the checkout for this purpose. The articles of goods, such as boxes of different shapes and sizes, bottles, packages, boxes, etc., are then arranged one by one on the screen, in which case only those surfaces which have the data field used to identify the goods need be directed towards the screen. Data fields in different objects thus appear in different directions directed to different places inside the screen. Furthermore, the data fields do not appear at fixed intervals for the reading station. The reading station must thus search for the data field and read the characters of the data lines in the direction of the data lines of the data field. The read characters are then routed as electronic signals to the cash register, which can also print the article number or article group on the cash register receipt.

The data field placed on the object is provided with a contrast line pattern (PIC) with several parallel lines with different distances and / or line widths. A contrast line pattern is intended to reliably and unambiguously distinguish a data field, e.g., a printed label, from other characters and line patterns that may be on the surface of an object in the vicinity of the data field. In addition, the contrast line pattern has a predetermined position and direction with respect to the data line inside the data field and can thus be used to determine the position and direction of the contrast line pattern - and with it the data lines - relative to the partition line partition angle to provide a partition raster in the data line direction. The reliable identification of a contrasting constant thus represents an essential step in reading data fields printed in plain characters.

DE-OS 2 338 561 discloses a method and apparatus of the type mentioned at the beginning, in which the contrast line pattern is identified only when the contrast line pattern itself is partitioned vertically in the direction of its lines and by means of which the pulse train contained in the video signal is the same as predetermined a pulse train corresponding to the contrast line pattern used. This is the case with the correlation method. The disadvantage in this case is that the partitioning of the image field in order to search for a contrast line pattern must take place in a very small angular step until the partition line intersects the contrast line pattern vertically, in which case the search time is undesirably large. As a result, the blurred printed edges of the lines of the contrast line pattern become disturbingly visible and possibly prevent the divided contrast line pattern from being recognized as such because the pulse train included in the video signal differs from the reference pattern in memory. As a result, either the search event is repeated or the contrast line pattern cannot be identified at all, the data field then remains unrecognizable.

It is an object of the invention, on the other hand, to provide a method and apparatus of the kind mentioned at the beginning, which enables the rapid and reliable identification of contrast line images and operates extensively independent of blur at the edges of contrast lines.

This problem is solved by a method according to the invention at the beginning, so that the lengths of the overlapping bright-dark periods (T1-T1) of the video signal are measured and presented as binary computational modes (TC1-TCa) - computational modes (TC1) to identify the k 67633 contrast line pattern (PIC). TC ^) give addresses to a two-dimensional table containing a wait field with predefined criteria for the ratio of two consecutive period lengths of periods (T1-T ^) - a counter mode (TCN) corresponding to one period length (TN) gives the table row address and the next period length (TN + 1 ) gives the address of the column of the table - generates a signal (LPIC1, LPIC2, LPIC3) when the ratio of the two successive period lengths is within a predetermined value range, and - outputs an identification signal (PIC OUT) when the number of subsequent predetermined addresses in the contrast line pattern is repeated. each time a signal is generated (LPIC1, LPIC2 , LPIC3).

The invention also relates to an apparatus for solving a set task, equipped with an optoelectronic scanning apparatus having a reversible scanning raster, which outputs a binary video signal corresponding to at least a line-scanned image field an identification field for the position and direction of a single data line and comprising a plurality of parallel lines at different distances and / or line widths, and equipped with hardware for orienting the scan raster parallel to the data line and for reading the scanned characters of the data line. Such an apparatus according to the invention is characterized in that the decoder apparatus comprises a counter circuit which receives the video signal and determines the period lengths of successively overlapping periods of the video signal and gives them as counter modes (TC1-TC4), that the decoder apparatus (2 to 40) contains at least one table (PROM 28) via the port connection (16-26), the counter modes corresponding to pairs of consecutive period lengths (TCI, TC2; TC2, TC3; TC3, TC * 1 ..) and which in each case give a signal (LPIC1, LPIC2, LPIC3) when the ratio of the two successive period lengths is predetermined -with a predetermined value range corresponding to the ratio of the corresponding periods of the contrast line pattern, and that the apparatus is provided with an operating circuit (3 ^, 36, 38) which outputs a detection signal (PIC OUT) from a predetermined number of consecutive signals (LPICI, ...).

The advantages of the invention are in particular that the contrast line image 67633 c

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is detection depends only on whether the ratio of successive, overlapping period lengths of the video signal is within a narrow range of values, so that the contrast line pattern is also reliably identified by diagonal contrast line partitioning because the successive ratios of successively measured period lengths of the video signal are unchanged. Thus, in order to reliably identify the contrast line pattern, it is sufficient to divide the contrast line pattern at any angle, by which all the contrast lines are completely exceeded. The search for a contrast line pattern can thus take place with a relatively large angular step, i. relatively quickly.

Since the decoding of the video signal to find the contrast line pattern must take place with respect to the video signal in real-time processing, i. essentially simultaneously with the capture of the video signal to ensure that the contrast line pattern is identified anywhere within the video signal, determining whether the ratio of successively measured period lengths is within a predetermined range, not by dividing but by moving to a reference signal when the two period lengths compared with each other are in a predetermined waiting field in the table, within which the quotient of the period lengths compared with each other has a value range corresponding to the quotient of the corresponding period lengths of the searched contrast line pattern. This avoids the time- and hardware-consuming division calculation method and maintains in real time the real-time use of the video signal.

It is better if the comparison table is formed as a two-dimensional fixed programmed memory (PROM). The different possible discrete values of the first measured period length indicate different lines of the fixed programmed memory. The different discrete values of the period measured below indicate the different columns of the fixed programmed memory. The waiting field is determined so as to include all memory locations where the quotient of the period length placed in the row address and the column length is within a predetermined value range. If the memory location 6 67633 Kalle is given an address inside the waiting field, then the fixed programming memory transmits a reference signal having the first amplitude, which means partial identification of the contrast line pattern. If, on the other hand, the memory location bound via the row address and the column address is outside the waiting field, then a reference signal having a second amplitude is transmitted, which means that the quotient of the successive period lengths compared to each other is outside the predetermined value range. When a second amplitude reference signal appears, the decoder devices are reset and are then ready to perform a new recognition and decoding step.

It is better if two comparable period lengths are entered in each case in a separate comparison table with its own waiting field and tested for their quotient value. It is better if each separate comparison table is implemented as a separate fixed programmed memory PROM in order to simplify the control logic of the decoder devices.

According to a preferred embodiment of the invention, the first fixed programmed memory has a first and a second.

to compare its period length, and with another fixed programmed memory to compare the second and third period lengths, etc. 8-bit memory locations. Thus, 8 comparison tables can be stored in fixed programmable memories, each with its own waiting field, forming a first table of e.g. the first bit of memory locations, a second table of the second bit of memory locations, etc. the installability of the inventive equipment has been increased.

The binary video signal has, for example, when the partition beam passes over the darkly colored area of the data field, a first amplitude Hi, and has a second amplitude Lo when the partition beam passes over the bright unmarked area of the data field. The order of the amplitudes Hi and Lo is arbitrary, it is also possible for both amplitudes to have a second order with respect to the bright and dark areas of the data field 7 6 76 3 3.

It is better if the periods of the video signal, the length of which is indicated, each extend from one rising edge to the next rising edge and overlap from the falling edge between these rising edges to the next falling edge of the video signal. The third section then extends from the second rising edge to the next rising edge, etc. In such a way that the periods each extend from rising edge to rising edge or falling edge to falling edge, it is ensured that the sharp edges of also identifies contrast line patterns obtained under different printing conditions.

To increase the recognition certainty, contrast line patterns with a predetermined length of the mark-free pre-zone can be used, the pre-zone being placed before the first contrast line. It is better if the measurement of the period lengths takes place only after a character-free pre-zone of a predetermined length appears in the video signal.

It is better if the measurement of the period lengths ends when any period length exceeds a predetermined maximum value equal to the maximum period length present in the contrast line pattern. It is better if the continuous measurement of the cycle lengths also ends when the ratio of two successively measured cycle lengths is outside a predetermined value range. In both cases, operation is suspended at the earliest possible time and the decoder hardware is restored to its active state.

It is better if the continuous measurement of the period lengths also ends when a character-free intermediate zone of a predetermined duration is partitioned, which corresponds to the same equalization interval between the lines of the contrast line pattern. The decoder hardware is then returned to the active state and is then ready to perform a new operation.

67633 o - o

It is better if the contrast line pattern is still character free. a post-zone whose length corresponds, for example, to the length of a character-free pre-zone. The contrast line pattern detection signal is transmitted only when the video signal also includes a predetermined length of the character-free trailing zone.

In order to increase the redundancy of the detection event and reduce the probability of error by its a-j, it is better if the same rows are partitioned n times, and the contrast line pattern detection signal is transmitted only after the contrast line pattern is detected n times in succession.

It is better if the lengths of the overlapping periods are measured digitally and calculated for this purpose in a calculator circuit. The counter circuit has a timer circuit that produces gate pulses of the same length as the corresponding periods of the video signal. To measure the length of each period of the video signal, each is provided with a calculator to which the port pulses of the corresponding period are applied to the port input. The calculator inputs of the calculators are connected to a pulse generator which provides synchronization pulses to the calculator during adjacent gate pulses. The final state of the separate counters then corresponds to the time length of the corresponding gate pulses and thus the corresponding periods. Sequentially computed cycle values give the address to the corresponding fixed-programmed memory, after which the subsequent compute value of the cycle is calculated, so that the calculation of the next compute values of the cycles can still continue.

In the following, the operation examples of the invention will be explained in more detail with the aid of the drawings. They present:

Figure 1 is a first prefix of a contrast line pattern in a data field with a single data line;

Figure 2 is another representation of a contrast line pattern in a data field;

Figure 3 is a third representation of the contrast line pattern in the data field;

Figure 4 is the light-dark distribution of the different contrast line patterns transverse to the contrast lines;

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67633

Figure 5 is a period of a video signal corresponding to the contrast line pattern of Figure Aa as a function of time;

Figure 6 is a block diagram of a counter circuit of a decoder apparatus;

Figure 7 is a block diagram of a decoder hardware comparison table;

Figure 8 extended operation of the decoder hardware comparison table;

Figure 9 is a block diagram of the operation circuit of the decoder apparatus;

Figure 10 is a schematic representation of the structure of the comparison table;

Figure 11 is a pulse diagram of the pulses produced in the timer circuit of the counter circuit;

Figure 12 Pulse diagram of the pulses modified in the selection circuit.

Figures 1 to 3 show various identifiers 50, e.g. adhesive price tags, affixed to the package or to an item and appearing on the screen in any a-position and direction. The screen is determined, for example, by means of an optical aperture angle of a light spot partitioning device, e.g. a vidicon, at which the screen is first partitioned in rows, in a row-shaped partition raster.

The identifiers 50 each have a data field containing opposing characters 52 on at least one data line 51 to identify goods with such an identifier. It is preferable that the characters consist of clear characters of some known machine-readable type of writing, e.g., OCR-A writing or OCR-B writing. In a predetermined position and direction with respect to the data line, a contrast line pattern 5A - also called a position identification code PIC - is placed with u-seven parallel contrast lines at different distances and / or line widths. The contrast line pattern is placed according to Fig. 1 before the data line, according to Fig. 2 below the data line, according to Fig. 3 at the end of the data line. The contrast line pattern 5A is asymmetrically formed transversely to the contrast lines so that the data field is identified with respect to the beginning and end of the data lines. The contrast line patterns shown in Figures 1 and 2, hereinafter referred to as the PIC pattern, have a mark-free front zone 56 and likewise a mark-free post-zone 58.

Although the PIC patterns are each shown with only three lines, PIC patterns of more than three lines can also be used. Further, the PIC patterns can be placed - in contrast to Figures 1 to 3 - in a different position and direction with respect to the data lines, and further two or more PIC patterns are placed in one identification field 50.

As shown in Fig. 1, the screen or the image corresponding to the screen is divided stepwise by at least one partition row 60 step angle oC. It is essential that before reading the data lines, the PIC pattern is first reliably identified, and its position and orientation relative to the partition beam 60 determined, because then the characters included in the data line can be read by raster partition.

Figure A shows the light-dark distribution of various three-line PIC images transverse to the line direction. The lines are all arranged asymmetrically and thus can be used according to the invention.

Figure 5 shows the flow of the video signal. The video signal is obtained by displaying the PIC pattern of Fig. Aa as an electrical, binary signal, wherein the dark region of the PIC pattern has an amplitude Hi and the bright region of the PIC pattern has an amplitude Lo. Any bright-dark oscillations within the discrete lines and gaps of the PIC pattern are removed from the electrical signal immediately after partitioning. In the period of the video signal according to Fig. 5, a character-free pre-zone corresponding to zone 56 in Fig. 1, a first period T1 from the first rising edge to the second rising edge, a second period T2 from the first falling edge to the second falling edge, a third period T3 from the second rising edge to the third rising edge, and a after zone 1.

The decoding of the PIC pattern, e.g. according to Fig. 5, takes place according to the so-called del-spacing method, which in each case tests whether 11 67633 consecutive and overlapping periods, i.e. T1, T2 and T2, T3 and T3:, TA are in a predetermined relationship with each other, which is given by the PIC pattern to be decoded. If the quotient value of successive, overlapping period lengths is within a predetermined value range, where the widths of the range are given by weight blur and digitization blur, then the PIC pattern is most likely to be searched.

Figure 6 shows a counter circuit which forms the input of the decoder apparatus according to the invention and calculates the period lengths T1 to TA and makes them available as binary values for later operation. The counter circuit includes a timer circuit 2 to which a video signal VIDEO is applied, which outputs a first gate signal from the first output signal from the first rising edge to the second rising edge, a second output signal T2 from a first rising edge of the video signal and from the fourth output a second gate signal TA from the second counting edge to the next, third counting edge, cf. pulse diagram according to figure 11. The gate signals T1 to TA are each fed to the gate inputs G1 to GA of one of the counters 6, 8, 10, 12. Each counter 6 -12 receives synchronization pulses from its counter input CT1-CTA pulse generator 1A, which counters 6-12 count as long as the gate signal T1-TA exists. At the outputs of the counters 6-12, the transmitter mode TC1 to TCA then displays a measurement of the length of the gate signals T1 to TA.

In the timer circuit 2, an operating signal E2 is produced from the falling edge of the gate signal T2, an operating signal E3 is output from the falling edge of the gate signal T3, and an operating signal EA is output from the falling edge of the gate signal TA and is sent to separate outputs. The operation signal list EA further provides a signal PWAIT, the length of which corresponds to the character-free post-zone after the end of the gate signal TA, and which is sent to a separate output.

The counter circuit further includes a reset circuit A which receives the video signal VIDEO, and a separate input for the external

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67633 at the beginning of each partition line of its reset signal RESET IN. The reset circuit A provides a reset signal RESET to the reset inputs RS1 to RSA and timer circuit 2 of counters 6-12 and resets counters 6-12 and timer circuit 2 to an active state if the video signal contains a character-free period - amplitude Lo - greater than the maximum assignment interval of the PIC pattern lines. between this, the maximum execution interval being given by the maximum precision within the PIC pattern, multiplied by the maximum allowable focusing angle.

The counter circuit further includes a bypass detection AO which receives a bypass signal from the bypass output 0V1 - OVA of the counters 6-12 and then gives a reset signal OV RESET and thus the decoder hardware is returned to the new standby state.

Figure 7 shows an embodiment of a decoder hardware comparison table. The comparison table contains the fixed programmed memory PROM, 28. The PROM 28 is arranged so that the counting mode TC1 of the counter 6 gives an address to separate rows of the memory matrix, and that the counting mode TC2 of the counter 8 gives an address to the separate columns of the first memory matrix. The calculation modes TC1 and TC2 are routed via the port connections 16, 18 after the calculation of the calculation mode TC2 by means of the operation signal E2 to the memory PROM 28. Within the first memory matrix, a waiting field is predetermined, comprising memory locations where the queue address and column address quotient are within a predetermined value range. This value range corresponds to the quotient of the first period length and the second period length of the PIC pattern used. If the calculation modes TC1 and TC2 give an address to the memory location within the waiting field, a reference signal having a first amplitude, e.g. Hi, is transmitted, which means that information corresponding to one part of the PIC pattern used was partitioned.

In order to perform a comparison of the port pulses T2, T3 in a corresponding manner, the counting mode TC2 of the second calculator 8 assigns an address to the rows of the second memory matrix, and the counting mode TC3 of the third counter 10 assigns an address to the columns of the second memory matrix. The address is entered after the counter mode TC3 has been calculated and the counter modes TC2 and TC3 have been routed by means of the operating signal 13 67633 E3 via the port connections 20, 22 to the memory PROM 28. Inside the second matrix, there is also a predetermined wait field comprising those memory locations whose quotient of row address and column address is within a predetermined value range equal to the quotient value range of the periods corresponding to the port signals T2 and T3 in the PIC pattern. If an address is given to the memory location in the waiting field, a reference signal having a first amplitude, e.g. Hi, is sent. By assigning an address to the memory location outside the waiting field, a reference signal having a second amplitude Lo is transmitted.

The comparison of the calculation modes TC3 of the third calculator 10 with respect to the calculation mode TC4 takes place in the same manner by assigning addresses to the rows and columns of the third memory matrix. The matrix also includes a waiting field, whereby by giving the address to the memory location inside the waiting field, a reference signal having a first amplitude Hi is transmitted. The addressing of the third memory array occurs after the calculator state TC4 of the fourth calculator 12 has been calculated and the operation signal E4 sends the calculator bars TC3 and TC4 via gate connections 24 and 26 to the memory PROM 28. Gate connections 16 to 26 consist of AND gates. The reference signals LPIC1, LPIC2 and LPIC3 are read by means of the read signals EL2, EL3 and EL4, which are obtained by decelerating the operation signals E2, E3 and E4 in the deceleration circuit 30, cf. pulse diagram according to figure 12. Reading should only take place after the assignment of addresses to the first, second and third memory matrices has become serious.

Alternatively, for the embodiment of Figure 7, a first memory matrix may be implemented with the first fixed programmed memory, PROM1, a second memory matrix with a second fixed programmed memory, PROM2, and a third memory matrix with a third fixed programmed memory, PROM3, because then memory.

The fixed programmed memory 28 has memory locations of n bits each. Since only one bit of the memory locations included in the waiting field is reserved for predetermining the waiting field, 8 different waiting fields for 8 different PIC patterns can be stored simultaneously in the PROM memory, whereby a first waiting field is stored in the memory PR0M1 for each first bit of the memory locations. for each second bit of memory locations, etc. Applies to memories PR0M2 and PR0M3, respectively. For each particular PIC pattern, the addressing of the rows and columns must then be selectively assigned to the corresponding bits of the memory locations. Further, a selector 32 is connected to the memory PROM 28, which selectively reads the reference signals LPIC1, LPIC2 and LPIC3 from the respective bits of the memory locations and sends to its output the operation signal MUX formed from the reference signals LPIC1, LPIC2 and LPIC3 for operation.

Figure 9 shows the operation circuit of the decoder equipment. The cache 34 receives the operation signal MUX PIC and sends the reference signal LPIC1 - it indicates that the value TC1 / TC2 is within a predetermined range - as well as the reference signal LPIC2 and the reference signal LPIC3. The input takes place by transmitting read signals EL2, EL3 and EL4, which occur mainly simultaneously with the reference signals LPIC1, LPIC2 and LPIC3, cf. pulse diagram according to Fig. 12. After all the reference signals in the cache have been taken from the memory as burst signals LPIC1 ', LPIC2', LPIC3 ', these memory signals are sent to AND gate 36, which transmits the output signal LPIC when all memory signals LPIC1', etc. have the first amplitude. , which corresponds to the first amplitude of the reference signals LPIC1, etc., cf. Figure 12. The output signal LPIC is applied to the operating circuit 38, which receives the video signal VIDEO and the waiting signal PUAIT from the timer circuit 2. The operation circuit 38 transmits the detection signal PIC OUT when the video signal VIDEO remains during the existence of the waiting signal PWAIT at the amplitude value Lo, which detects the character-free background. This ensures that the decoded line pattern of the character-free post-zone is followed. The zone is the same as the post-zone 58 of the PIC pattern.

The operation circuit 38 is reset by an external reset signal RESET III, which then sends a reset signal RESETA to the cache 67633 34 and similarly resets it for new use. The cache is further reset with the bypass reset signal OV RESET when one of the counters 6-12 detects an override.

Fig. 10 shows a schematic representation of how a comparison table, e.g. a partial comparison table of the memory PR0M1, for arranging the quotient TC1 / TC2 is arranged. The table is presented as a memory matrix, the rows of the table are marked with binary addresses. The columns of the table are also marked with binary addresses, in which case a 5-bit representation is selected according to a better embodiment of the decoder apparatus according to the invention. All memory locations with a certain value of the quotient of row and column addresses are in one line, on the so-called wait line, surrounded by a waiting field, inside which are all memory locations whose address quotients are within a predetermined value range. Calculator modes TC1 to TC4 are likewise transmitted in 5-bit words. Calculator mode TC1 gives an address to the rows of the table, calculator mode TC2 gives an address to the columns of the table.

Claims (20)

16 67633 A method for identifying objects which appear on a screen in any position and direction and at any time and in each case indicate on the surface of the screen an identification field (50) comprising characters in at least one data line (51) and at least one contrast line pattern (5 ^) » as an identifier for the position and direction of the data line, and wherein the contrast line pattern has a plurality of parallel lines at different distances and / or line widths, sweeping the screen in lines and generating a binary video signal corresponding to , the second method step determines the position and direction of the data line relative to the screen, and the third method step performs a raster scan in the direction of the data line and the characters are read and decoded, characterized in that - contrast to identify the line pattern (PIC), the lengths of the overlapping bright-dark periods (T1-T4) of the video signal are measured and presented as binary counter modes (TC1-TC ^) - the counter modes (TC1-TC ^) give addresses to a two-dimensional table containing a waiting field with predefined criteria for the ratio of the periods (T1-T ^ O to two consecutive period lengths - the counter mode corresponding to one period length (TN) gives the table row address and the counter mode corresponding to the next period length (TN + 1) gives the table column address - a signal is generated (LPIC1, LPIC2 , LPIC3) when the ratio of the two successive period lengths is within a predetermined value range, and - an identification signal (PIC OUT) is output when a signal is generated (LPIC1, LPIC2, LPIC2) after a predetermined number of successive address assignment steps of the contrast line pattern. Method according to Claim 1, characterized in that the waiting field of the table is in each case limited by a row and a column, in which case there are minimum and maximum period lengths. 17 67633 Method according to Claim 1 or 2, characterized in that the calculation modes of the two successive period lengths in each case give the addresses to a separate table with its own waiting field. Method according to claim 3, characterized in that the individual tables have different waiting fields for successive period lengths of different contrast line patterns. Method according to one of the preceding claims, characterized in that the periods of the video signal are measured in each case from the rising edge to the next rising edge and overlapping from the falling edge between these rising edges to the next falling edge. Method according to one of the preceding claims, characterized in that the contrast line pattern has a character-free pre-zone having a predetermined length, and in that the measurement of the period lengths begins only when a character-free pre-zone of a predetermined length is detected in the video signal. Method according to one of the preceding claims, characterized in that the measurement of the period lengths ends when the period length exceeds a predetermined maximum value which corresponds to the maximum period length present in the contrast line pattern. Method according to one of the preceding claims, characterized in that the continuous measurement of the cycle lengths ends and a new measurement begins when the ratio of two successively measured cycle lengths is outside a predetermined value range. Method according to one of the preceding claims, characterized in that the continuous measurement of the period lengths ends and a new measurement begins when a character-free intermediate zone of a predetermined duration corresponding to the maximum interval of the lines of the contrast line pattern is detected in the video signal. Method according to one of the preceding claims, characterized in that the contrast line pattern has a character-free post-zone of a predetermined length, and that the detection signal (PIC OUT) is output only if the video signal has a character-free post-zone of a predetermined length. Method according to one of the preceding claims, characterized in that the period lengths are digitally multiplied by a predetermined period of time and are further processed as binary signals. Method according to one of the preceding claims, characterized in that the same line of the image field is scanned n times and that the identification signal (PIC OUT) is given only after the contrast line pattern has been detected n times in succession. An apparatus for performing a method according to any one of claims 1 to 12, provided with an optoelectronic scanning apparatus having a reversible scanning raster which outputs a binary video signal corresponding to at least one identification field for the position and direction of a single data line and comprising several parallel lines at different distances and / or line widths, and equipped with means for orienting the scanning raster parallel to the data line and reading the scanned characters of the data line, characterized in that decoder equipment (2- h) a counter circuit (2, 6-14) which receives the video signal and determines the period lengths of successively overlapping periods of the video signal and outputs them as counter modes (TC1-TC4), that the decoder mode the arrays (2-40) include at least one table (PROM 28) that receives, via the gate link (16-26), counter modes corresponding to pairs of consecutive period lengths (TCI, TC2; TC2, TC3; TC3, TC4 ...) and which in each case gives a signal (LPIC1, LPIC2, LPIC3) when the ratio of the two successive cycle lengths is within a predetermined value range corresponding to the ratio of the corresponding cycles of the contrast line pattern, and that the apparatus is activated (34, 36, 38), which outputs a detection signal (PIC OUT) from a predetermined number of consecutive signals (LPIC1, ...). Apparatus according to claim 13, characterized in that the counter circuit (2, 6-14) comprises a timer circuit (2) which generates gate pulses (T1, T2, T3, T4 ...) corresponding to overlapping periods of the video signal whose pulse length it is determined from the successive rising edges or successive falling edges of the video signal that the gate pulses (T1, T2, T3, T4 ...) are each controllable to the gate input of one counter (6-12), that the counter inputs of the counters (6-12) are connected to a pulse generator (14 ) and that the calculators calculate the gate pulses and give the addresses (TC1-TC4) to the table (28) as digital counter modes. 67633 ί n - y · An apparatus according to claim 14, characterized in that the counter circuit (2, 6-14) includes a bypass detection (40) which, after bypassing the counter (6-12), resets the decoder equipment (2-40). Apparatus according to one of Claims 13 to 15, characterized in that the table (28) is formed as a two-dimensional fixed-programmed memory (PROM), that the first period length counting mode (TC1-TC4) assigns an address to the period length calculator mode (TC1-TC4) gives an address to the uniquely arranged columns of the fixed programmed memory, that the waiting field comprises those memory locations where the quotient of the row address and the column address is in a predetermined value range, and that when the address LPIC1 . Apparatus according to Claim 16, characterized in that each of two successive counter values (TCI, TC2; TC2, TC3; TC3, TC4 ...) has its own fixed-programmed memory (PROM 1, PROM 2, PROM 3 ...), which has its own waiting field. Apparatus according to Claim 17, characterized in that the sequentially computed calculation modes (TCI, TC2; TC2, TC3; TC3, TC4 ...) assign addresses in pairs to the fixed-programmed memory (PROM1, PROM2, PROM3) arranged in each case when the counter value of the latter period is calculated, and when the timer circuit (2) gives an operation signal (E2, E3, E4) to activate the port connection (16, 18; 20, 22; 24, 26, ...) in front of the fixed programmed memory. Apparatus according to one of Claims 16 to 18, characterized in that each fixed programmed memory (PROM) contains selectively assignable waiting fields for different contrast line patterns, and in that the calculation modes (TC1-TC4) arranged in different waiting fields can be derived for operation (34, 36, 38). from the memory using the connected selector (32). Apparatus according to one of Claims 13 to 19, characterized in that the operating circuit (34, 36, 38) comprises a cache (34), an AND gate (36) connected to it and an operating circuit (38). Apparatus according to one of Claims 13 to 20, characterized in that it is provided with a reset circuit (4) which receives a? 0 67633 video signal and at the beginning of each scan line an external reset signal (RESET IN), that the reset signal (4) RESET) when the video signal contains a character-free zone greater than the maximum scan interval between the lines of the contrast line pattern, that the reset circuit (4) gives a reset signal (RESET) when an external reset signal (RESET IN) exists, and that the reset signal (RESET) can be derived for the calculator (6-12) and the timer circuit (2) for resetting.